Psychoactive drugs can be defined as 'chemicals that influence consciousness or behaviour by altering the brains chemical message system' (Schacter et al, 2012). Different drugs can affect the brain in different ways either by intensifying or dulling transmissions. They will alter neural connections by preventing neurotransmitters bonding to the post synaptic neurons in the brain, inhibiting the re-uptake of neurotransmitters or enhancing the bonding and transmission of neurotransmitters.
Neurotransmitters are 'chemical messengers that carry signals between neurons in the body' (Cherry K, 2014). They are released after an action potential has reached the pre-synaptic terminal. The neurotransmitter then crosses the synaptic gap to reach the receptor site of the post-synaptic neuron. Reuptake of the neurotransmitter is when it attaches to the receptor site and is reabsorbed by the neuron so it can be used again to pass along another action potential. They can be categorised as one of six types: acetylcholine, amino acids, neuropeptides such as endorphins, monoamines such as serotonin and dopamine, purines and lipids and gases (Cherry K, 2014).
Psychoactive drugs are classified into five different groups depending on how they affect the brain. In this essay I will be looking at three of these groups: stimulants, depressants and hallucinogens and how they exert influence on neural processing.
Stimulants are a type of psychoactive drug that increase the brains activity. These drugs can amplify alertness, mood, and awareness. Drugs classed as stimulants include: caffeine, nicotine, cocaine, amphetamines and prescription drugs.
Cocaine is a crystalline tropane alkaloid acquired from the leaves of a coca plant. It is thought to work by blocking a dopamine active transporter in the brain and therefore increasing the availability of free dopamine in the brain (Volkow et al, 1997). It does this by binding to the dopamine active transporters which prevent the neuron re-absorbing the extra dopamine in the synaptic cleft which results in an increased level of dopamine in the extracellular spaces among neurons. Dopamine is the chemical associated with pleasure in the brain. It is released throughout pleasurable situations and also stimulates one to seek out the pleasurable activity (Mandal A, 2014). Therefore the increase of free dopamine in the brain as a result of taking cocaine will result in this heightened feeling of pleasure. There is also mounting evidence that cocaine can actually increase dopamine release instead of just blocking it's re-absorption. In a study by Venton. J et al (2006) they observed the actions of cocaine on dopamine release by using electrochemical detection to measure how much extracellular dopamine was in the sub cortical part of the forebrain in anesthetized mice. Cocaine was discovered to increase the levels of dopamine produced by electrical stimulation of neurons related to dopamine. Even after a pre-treatment with...